We present Sunyaev-Zeldovich effect (SZE) imaging observations of
three distant (z > 0.8) and highly X-ray luminous clusters of
galaxies, Cl J1226.9+3332, Cl J0152.7-1357, and MS 1054.4-0321. Two of
the clusters, Cl J1226.9+3332 and Cl J0152.7-1357, were recently
discovered in deep ROSAT X-ray images. Their high X-ray luminosity
suggests that they are massive systems, which, if confirmed, would
provide strong constraints on the cosmological parameters of structure
formation models. Our SZE data provide confirmation that they are
massive clusters similar to the well-studied cluster MS
1054.4-0321. Assuming the clusters have the same gas mass fraction as
that derived from SZE measurements of 18 known massive clusters, we
are able to infer their mass and electron temperature from the SZE
data. The derived electron temperatures are 9.8^{+4.7}_{-1.9},
8.7^{+4.1}_{-1.8}, and 10.4^{+5.0}_{-2.0} keV, respectively, and we
infer total masses of ~2 × 10^14 h100^{-1} M_sun within a radius of
65" (340 h100^{-1} kpc) for all three clusters. For Cl J0152.7-1357
and MS 1054.4-0321, we find good agreement between our SZE-derived
temperatures and those inferred from X-ray spectroscopy. No
X-rayderived temperatures are available for Cl J1226.9+3332, and thus
the SZE data provide the first confirmation that it is indeed a
massive system. The demonstrated ability to determine cluster
temperatures and masses from SZE observations without access to X-ray
data illustrates the power of using deep SZE surveys to probe the
distant universe.